Are there really new ways to build roads? Well, yes. But whether or not those new ways are feasible is another question.
The actual design, construction and road maintenance systems for roads, streets and highways may appear to be set in stone/asphalt. Indeed, some of the fundamentals of what defines pavement – layers of gravel, rock and sand held together with emulsifiers, plus a sloping surface to rid the road of precipitation – are remarkably similar since the days of the Roman Empire and its many roads.
But the exigencies of the modern economy and of public safety, as well as the costs associated with building and repairing roads, call for something better. It’s clear that the tab for building new roads is high: According to the American Road & Transportation Builders Association (ARTBA), construction of a new four-lane highway can range from $4 million per mile in rural areas to $10 million per mile in urban areas. Further, ARTBA says that American taxpayers spend more repairing and maintaining existing roads and bridges than building new – more than $135 billion on federal, state and local roads per year, an amount considered inadequate for addressing the poor conditions of existing infrastructure.
So what are the current innovations driving toward smarter, longer-lasting asphalt? What can make our tax dollars stretch further? How can our roads be safer, and less likely to inflict damage to our cars, trucks, and buses?
The National Center for Asphalt Technology (NCAT) at Auburn University has been working on asphalt R&D since 1986. Working with the Federal Highway Administration and state-level highway agencies, as well as private-sector construction companies, NCAT develops and evaluates new products, new design technologies, as well as construction methods that lead to better pavement.
It’s important to note that not all innovation is something visible to the eye or leading to revolutionary changes. The technical variables in road building are indeed exciting, even if some of the innovations are something only a civil engineer could appreciate. A running list of links to research reports from NCAT can be found here
Meanwhile, Engineering & Technology magazine has done a pretty good job of reporting on asphalt innovation that the average motorist can relate to. Looking at new ways of building roads, it provides a summary of four new technologies that are in various stages of R&D:
Plastic waste replacing bitumen: A Scottish firm, MacRebur, is developing an asphalt mix that uses pellets and flakes sourced from household plastic waste to replace a portion of the petroleum-based binder (bitumen) used in asphalt. Developers report that while oil-based bitumen isn’t entirely eliminated from the process, it provides a double benefit by finding a reuse for plastic waste while reducing dependency on oil for road building and associated greenhouse gases. Importantly, it introduces no new requirements in the manufacturing and application processes. The company built its first American plastic-mix road on the University of California San Diego campus, and is soon to open a plant nearby to make and sell the mix to California builders.
Waste plastic modular road components: Prefabricated and hollow road sections made of recycled plastic are another approach to using waste to build pavement. The aptly named PlasticRoad company, based in The Netherlands, includes a cavity separating the top (surface) and lower sides of the modular sections that can be used for drainage, utilities (pipes and cables), and heating elements to melt winter ice. The first installation in 2018 is a bike path in Zwolle, NL with future plans for vehicular roads and airport runways.
Paper manufacturing lignin: Plastic isn’t the only waste material being tested as a road-building material. A by-product of paper manufacturing, lignin, can entirely replace bitumen in road building. The material is under test at Wageningen University, also in the Netherlands. One stumbling block: Lignin is currently expensive and therefore offers no economic advantage over petroleum-based materials.
Bio-bitumen: Not satisfied with just plastic waste, researchers at Aston University (Birmingham UK) are looking at the full stream of household garbage to create a bitumen substitute. It uses plastic along with paper, textiles, and organic materials that is ground and heated (500 degrees Celsius) into a dark goop. The Birmingham Council is looking at testing it on local roads.
Because all of these newer technologies are not yet proven, we cannot say they will be pothole-free in a decade or two. Suffice it to say we will be keeping an eye on how things develop – and perhaps stay intact – from here.
